Distinct from Conversational Troping in that a Discussed Trope will have some relevance to the situation at hand, and distinct from an Invoked Trope in that an Invoked Trope is always either played straight or expected by at least one character to be played straight.

Later, Haruhi, Mikuru, and Koizumi discuss Oblivious to Love in front of Kyon. He still doesn't get it.

In the "Teraverse" story It's Just A Habit by "Captain Boulanger", the POV character Marie O'Neill is a Catholic eucharistic minister -- a variety of Catholic lay-clergy with a very limited remit -- and in one chapter, she remarks on the difference between the movies and reality when it comes to the Sacrament of the Anointing of the Sick (which, as she explains, the movies often get wrong as being the entirety of the "Last Rites" rather than only one component of them, and also is not only used in that context).

Rosewood: You know what I keep thinking about? You know the end of Butch Cassidy? Redford and Newman are almost out of ammunition, and the whole Bolivian army is out- out in front of this little hut?Taggart: Billy, I'm gonna make you pay for this.

The Boondock Saints pull this measure during a shopping scene where one character impedes himself with a large length of rope, because people in the movies always have it and always need it. Lampshaded later on.

The Lord Peter Wimsey stories tends to feature dialogue in which somebody discussing "If this were a mystery story..."

Particulalry common when his Love Interest Harriet Vane is present, as she is a writer of mystery stories.

Sam Vimes' Genre Savvy discussion of Clues in various Discworld books is another good literary example.

Discworld and Discussed Tropes go together like dwarves and gold. In Sourcery, an Evil Chancellor actually SAYS of some evil action he is undertaking, "I am the Vizier after all. It is rather expected of me."

This is taken to its logical extreme in Dr Hix, Professor of Postmortem Communications, who is contractually obligated to be mildly evil on a day-to-day basis, not to exceed aforementioned contractual standards. Will often loudly insist on this as part of Unseen University discussions.

The Black Jewels book Tangled Webs by Anne Bishop has a couple of examples, mainly because the villain is a hack author. Two characters who had been making fun of the author's cliché-ridden writing are trapped in a house that's trying to kill them while the author watches from inside the walls and records it all as fodder for his next book. At one point, the characters comment that in a horror story, this is exactly when one of them would be stupid enough to go into the cellar. As they're saying this, the cellar door slams shut of its own accord—if they had gone down the stairs, they would have been trapped. Later in the book, the (gay) male main character remarks to the female main character that this is the point in the story where they're supposed to have sex. They look at each other for a moment, and then the woman says, "So what do you want to do in the five minutes that would have taken?"

Robert A. Heinlein was particularly fond of having his characters do this, particularly ones who are established authors in-universe and who proceed to comment on the narrative structure of their own stories. The Cat Who Walks Through Walls is a prime example.

Otherland, by Tad Williams, contains an elaborately drawn out discussion of the Shaggy Dog Story trope throughout the novels, triggered initially by the presence of a Bushman character whose tribal mythology is largely based on the concept, and later getting folded into the main plot by means of the Other's manipulations and the hidden agenda of Mr. Sellars.

In The Shattering Prelude to Cataclysm, Thrall realizes that the Horde is suffering from the What Measure Is a Non-Human? trope, as many of the young warriors started out killing undead in the war against the Scourge, and thus are somewhat desensitized to killing living opponents, making them more keen on going to war with the Alliance.

An episode of Get Smart opens with Max receiving the name of a KAOS spy from a midget in an otherwise vacant warehouse. Max immediately tells the informant that he was surprised that he wasn't shot dead right before revealing the name. Because of the surprise, Max forgets the name and asks the informant to repeat it. The informant is then killed by a sniper before repeating the name.

The titular character of Castle does this CONSTANTLY. He's a big fan of CIA/NSA conspiracies, alien abductions, time travel and in an episode where a murder victim has a butler, he would dearly love to say "The Butler Did It."

Host segments on Mystery Science Theater 3000 were frequently dedicated to discussions that would deconstruct themes and tropes found in the movies the main characters were watching. The episode Eegah, for example, has one relating to the Missing Mom of the film, and how it was a plot setup commonly used in television of the period. The Bots also Lampshade the whole thing by pointing out they don't technically have a mom either.

Older Than Dirt: In The Epic of Gilgamesh, when the titular character is approached by Ishtar, who asks him to marry her. He then proceeds to list the examples of fictional characters[1] who ended up in a bad fate because of sleeping with divine beings.

In an episode of The Batman, Alfred worries that "This time, the butler may indeed have done it" in relation to a series of robberies from the Wayne household. Funny thing is? He did do it, under hypnosis. That was discovered quite quickly.

In the Code Lyoko episode "Sabotage", damage to the Supercomputer causes lots of bugs on Lyoko, including one that makes Ulrich's Avatar lose all colors. Playing along, he starts fighting a Tarantula Three Musketeers-style with his katana. (The French version also adds in a Shout-Out to Cyrano De Bergerac.)